A standard blade assembly for a meat chopper is normally carried on a noncircular-section portion of a shaft that is driven about its own axis at high speed. The individual blades of the assembly each have outer cutting portions formed with cutting edges and inner portions bolted or riveted to metallic support disks which each have a central hole complementary to the noncircular-section shaft portion. Normally the noncircular shaft portion is shaped like a regular polygon so the blades can be positioned in any of a plurality of equiangularly offset positions.
Such a system is described in German patent publication No. 2,338,145. In this arrangement the support disks are relatively massive and therefore also serve to space the blades axially apart, elastomeric layers being used to either side of each blade to reduce vibration and keep the assembly tight. Since the blade assembly is used to chop meat it is made of a high-quality steel that can resist the acids and the like it will be subjected to.
Even with such steel support disks, corrosion and metal failure is a problem. The support disks are damaged by so-called cavitation erosion resulting from the combined effect of various chemical agents such as salts, carbohydrates, albumin and water, all combined with various thermal and electrochemical factors that can erode even the toughest steels.
It has therefore been suggested to coat the support disks with a protective layer, such as of polytetrafluorethylene that largely resists chemical attack. Although such an expedient would seem to solve the problem, in practice such a coating is frequently damaged and quickly penetrated. The sharp bone splinters occasionally encountered are enough to breach the coating, leaving the underlaying material open for chemical attack. Even normal handling of thus coated parts can damage the coating.
Another suggestion has been to use light alloy support disks. Although such disks do indeed resist corrosion much better than steel disks, they react with many constituents of food that will pass through the meat chopper. Obviously a meat chopper that imparts a taste to the foodstuff it is processing is unacceptable. Such support disks are also normally extremely rigid, so that any vibration is not damped at all, but instead is effectively transmitted throughout the assembly.